U.S. patent number 6,384,381 [Application Number 09/866,086] was granted by the patent office on 2002-05-07 for oven device for rapid heating of food items.
This patent grant is currently assigned to Hatco Corporation. Invention is credited to Gerhard H. Wenzel, Allan E. Witt.
United States Patent |
6,384,381 |
Witt , et al. |
May 7, 2002 |
Oven device for rapid heating of food items
Abstract
An oven device for final finishing of a food item includes an
oven housing defining a heating cavity configured to receive at
least one food item to be heated, and an upper heating unit within
the oven housing above the heating cavity. The upper heating unit
includes a heating element that generates radiant heat directed
onto the food item in the heating cavity. The oven housing includes
at least one reflective panel for distributing radiant heat within
the heating cavity. The upper heating element includes a
rapidly-heating, high-intensity heating element capable of being
cycled on for final finishing of the food item when the food item
is received in the heating cavity, and capable of being cycled off
when final finishing is not being performed. The final finishing
typically includes browning a top surface of the food item, or
melting a topping onto the top surface of the food item.
Inventors: |
Witt; Allan E. (Brown Deer,
WI), Wenzel; Gerhard H. (Sussex, WI) |
Assignee: |
Hatco Corporation (Milwaukee,
WI)
|
Family
ID: |
24071980 |
Appl.
No.: |
09/866,086 |
Filed: |
May 25, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
520294 |
Mar 7, 2000 |
6262396 |
|
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|
Current U.S.
Class: |
219/411; 219/553;
219/543; 219/410; 219/409 |
Current CPC
Class: |
A47J
37/0623 (20130101); A47J 37/0641 (20130101); F24C
7/00 (20130101) |
Current International
Class: |
A47J
37/06 (20060101); F24C 7/00 (20060101); H05B
003/26 (); H05B 003/64 (); A21B 001/22 (); A47J
037/06 () |
Field of
Search: |
;219/405,409,410,411,412,395,398,552,553,685,543 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
EP Form 1507.0 Hatco Corporation Sep. 17, 2001..
|
Primary Examiner: Pelham; Joseph
Attorney, Agent or Firm: Foley & Lardner
Parent Case Text
RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent
application Ser. No. 09/520,294, filed Mar. 7, 2000, now U.S. Pat.
No. 6,262,396 entitled "Oven Device for Rapid Heating of Food
Items", which is hereby incorporated by reference.
Claims
What is claimed is:
1. An oven device for final finishing of a food item,
comprising:
an oven housing defining a heating cavity therein, the heating
cavity configured to receive at least one food item to be heated by
the oven device;
the oven housing including at least one reflective panel for
distributing radiant heat within the heating cavity; and
an upper heating unit disposed within the oven housing above the
heating cavity, wherein the upper heating unit includes an upper
heating element;
the upper heating unit configured to generate radiant heat which is
directed onto the at least one food item when the at least one food
item is received in the heating cavity, wherein the upper heating
element includes a rapidly-heating, high-intensity resistive ribbon
heating element capable of being cycled on for final finishing of
the at least one food item when the at least one food item is
received in the heating cavity, and capable of being cycled off
when such final finishing is not being performed, the resistive
ribbon heating element configured to provide radiant energy
directly to the food item.
2. The oven device of claim 1 wherein the reflective panel
comprises a metallic panel having a corrugated surface pattern.
3. The oven device of claim 2 wherein the corrugated surface
pattern has a longitudinal profile oriented parallel to a planar
orientation of the resistive heating element.
4. The oven device of claim 3 wherein the corrugated surface
pattern is linear and horizontal.
5. The oven device of claim 3 wherein the corrugated surface
pattern is linear and vertical.
6. The oven device of claim 1 wherein the reflective panel is
parallel to a back wall of the oven housing.
7. The oven device of claim 1 wherein the at least one reflective
panel is generally parallel to one or more of a back wall, a side
wall, a top or a base of the oven housing.
8. The oven device of claim 1 wherein the reflective panel has an
interchangeable reflective insert.
9. The oven device of claim 1 wherein the reflective panel is
unitarily formed.
10. The oven device of claim 1 wherein the reflective panel is made
from stainless steel.
11. An oven device for final finishing of a food item,
comprising:
an oven housing defining a heating cavity therein, the heating
cavity configured to receive at least one food item to be heated by
the oven device;
the oven housing including at least one reflective panel for
distributing radiant heat within the heating cavity;
an upper heating unit disposed within the oven housing above the
heating cavity, wherein the upper heating unit includes an upper
heating element;
a lower heating unit disposed within the oven housing below the
heating cavity, wherein the lower heating unit includes a lower
heating element;
the upper and lower heating units configured to generate radiant
heat which is directed onto the at least one food item when the at
least one food item is received in the heating cavity, the upper
and lower heating elements each including a rapidly-heating,
high-intensity resistive ribbon heating element capable of being
cycled on for final finishing of the at least one food item when
the at least one food item is received, and capable of being cycled
off when such final finishing is not being performed, the resistive
ribbon heating element configured to provide radiant energy
directly to the food item.
12. The oven device of claim 11 wherein the reflective panel
comprises a metallic panel having a corrugated surface pattern.
13. The oven device of claim 12 wherein the corrugated surface
pattern has a longitudinal profile oriented parallel to a planar
orientation of the resistive heating element.
14. The oven device of claim 13 wherein the corrugated surface
pattern is linear and horizontal.
15. The oven device of claim 13 wherein the corrugated surface
pattern is linear and vertical.
16. The oven device of claim 11 wherein the reflective panel is
parallel to a back wall of the oven housing.
17. The oven device of claim 11 wherein the at least one reflective
panel is parallel to one or more of a back wall, a side wall, a top
or a base of the oven housing.
18. The oven device of claim 11 wherein the reflective panel has an
interchangeable reflective insert.
19. The oven device of claim 11 wherein the reflective panel is
made from stainless steel.
20. An oven device for final finishing of a food item,
comprising:
oven housing means for defining a heating cavity for receiving at
least one food item;
resistive ribbon heating means within the oven housing means for
generating high-intensity radiant heat and for directing the heat
directly onto a top surface of the at least one food item when the
at least one food item is within the heating cavity;
means for distributing the radiant heat within the heating cavity;
and
means for cycling the radiant heat on for final finishing of the at
least one food item when the at least one food item is received
within the heating cavity and for cycling the heat off when such
final finishing is not being performed.
Description
FIELD OF THE INVENTION
The invention relates generally to an oven device for rapidly
heating food items. More particularly, the invention relates to an
improved oven device for rapid melting or browning of the top
surfaces of food items, which may typically involve melting or
browning toppings or side-dishes which have been applied onto or
beside pre-cooked food components. The oven device also provides
the capacity to simultaneously heat the plate or other support
assembly for the food items.
BACKGROUND OF THE INVENTION
In the restaurant business, components of individual food items or
of complete meals (e.g., hamburger patties; broiled beef; fried
chicken; etc.) are often pre-cooked at cooking locations around the
restaurant's kitchen. These pre-cooked food components are then
assembled into completed food items or meals before presentation to
the customer. During the final assembly process, various toppings
or side-dishes are served on or beside the pre-cooked components,
and the toppings or side-dishes are melted or browned before the
food items or meals are served. For example, sliced or grated
cheese is often melted onto a pre-cooked hamburger patty to make a
cheeseburger, or whipped potatoes are browned after being added as
a side-dish to a plate of fried chicken. Together with melting or
browning the top surfaces of the food items or complete meals, it
is often necessary or desirable to simultaneously heat the serving
plate or other assembly on which the food items or meals are served
in order to provide the perception of a fresh-cooked hot meal. For
example, Mexican restaurants typically serve fajitas on a sizzling
iron skillet. Ovens used to perform the finishing functions of
melting or browning the toppings of the food items before they are
served can be referred to as "thermal finishers".
One existing system for performing these functions employs a plate
heater to heat the serving plate, and a gas over-fired broiler
known in the restaurant industry as a "Salamander" broiler to
perform the final finishing (i.e., the melting or browning) of the
toppings or side dishes. This system, however, has significant
disadvantages. The over-fired gas broiler generates a tremendous
amount of heat (e.g., 40,000 to 60,000 BTUs), much of which is
wasted since the Salamander broiler must be left on continuously
since it takes a significant period of time to warm up, even though
the broiler is used for only a fraction of the time that it is
turned on. Also, since the Salamander broiler is open to the
kitchen, the high heat output level of the broiler heats up the
kitchen and requires the installation of kitchen exhaust fans in
order to exhaust the excess heat. Thus, the Salamander broiler is a
wasteful system for melting toppings and warming serving
plates.
Another existing system employs a conveyor oven which must also be
turned on all of the time, and is relatively slow in comparison to
the Salamander broiler. The slow heating time of this alternative
type of system is an important disadvantage in, for example, the
fast-food industry. In addition, since the entire plate or support
assembly passes through the heating cavity via the conveyor, the
entire plate including its rim becomes hot such that the plate
cannot be efficiently handled by food service workers without using
insulated gloves or other methods.
Thus, it would be advantageous to provide an improved oven device
for rapid heating of food items which overcomes these and other
disadvantages of existing systems. It would be advantageous to
provide such an oven device which can be turned on and off as
needed, thereby decreasing both energy usage and the amount of heat
vented into the kitchen as compared to an oven which must be left
on continuously. The decreased amount of heat vented into the
kitchen would allow the exhaust hood or other ventilation method
needed to exhaust the excess heat to be dispensed with, and would
result in savings in air conditioning and ventilation costs. It
would also be advantageous to provide an oven device for rapid
heating of food items capable of heating the items significantly
faster than is possible using existing conveyor oven systems. Also,
it would be advantageous to provide an oven device for rapidly
heating food items which is capable of heating only a portion of
the plate or support assembly for the items such that the plate or
support assembly could be efficiently handled by the restaurant's
food service workers. For example, it would be advantageous to
provide such an oven device wherein the rims of plates holding the
food items would not be subjected directly to the heat source and
would not be subjected to the radiant heat of the oven. This would
allow food service workers to pick up the plates by their rims
without using insulated gloves or other methods.
SUMMARY OF THE INVENTION
One embodiment of the invention provides an oven device for final
finishing of a food item. The oven device includes an oven housing
defining a heating cavity therein and an upper heating unit
disposed within the oven housing above the heating cavity, and at
least one reflective panel for distributing radiant heat within the
heating cavity. The heating cavity is configured to receive at
least one food item to be heated by the oven device. The upper
heating unit includes an upper heating element. The upper heating
unit generates radiant heat which is directed onto the at least one
food item when the at least one food item is received in the
heating cavity. The upper heating element includes a
rapidly-heating, high-intensity heating element capable of being
cycled on for final finishing of the at least one food item when
the at least one food item is received in the heating cavity, and
capable of being cycled off when such final finishing is not being
performed.
Another embodiment of the invention provides an oven device for
final finishing of a food item including an oven housing defining a
heating cavity therein, and at least one reflective panel for
distributing radiant heat within the heating cavity, and upper and
lower heating units disposed within the oven housing above and
below the heating cavity, respectively. The heating cavity receives
at least one food item to be heated. The upper and lower heating
units include an upper and a lower heating element, respectively.
The upper and lower heating units generate radiant heat which is
directed onto the at least one food item when the at least one food
item is received in the heating cavity. The upper and lower heating
elements each include a rapidly-heating, high-intensity heating
element which can be cycled on for final finishing of the at least
one food item when the at least one food item is received, and of
being cycled off when such final finishing is not being
performed.
Another embodiment of the invention provides an oven device for
final finishing of a food item including oven housing means for
defining a heating cavity for receiving at least one food item,
resistive ribbon heating means within the oven housing means for
generating high-intensity radiant heat and directing the heat onto
a top surface of the at least one food item when the at least one
food item is within the heating cavity, means for distributing the
radiant heat within the heating cavity, and means for cycling the
radiant heat on for final finishing the at least one food item when
the at least one food item is received within the heating cavity
and for cycling the heat off when such final finishing is not being
performed.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the
following detailed description, taken in conjunction with the
accompanying drawings, wherein like reference numerals refer to
like parts, in which:
FIG. 1 is a perspective view of an oven device for rapidly heating
food items (i.e., a thermal finisher) according to one embodiment
of the invention;
FIG. 2 is a front view of the oven device shown in FIG. 1;
FIG. 3 is a side view of the oven device shown in FIG. 1;
FIG. 4 is a rear view of the oven device shown in FIG. 1;
FIG. 5 is a top view of the oven device shown in FIG. 1, including
an illustration of the geometric arrangement of the internal
heating elements;
FIG. 6 is a diagram showing the layout of a timer board used by the
oven device of FIG. 1, which provides the user interface as also
shown in FIG. 2;
FIG.7 is a rear exploded perspective view of a reflective wall
panel for the oven device;
FIG. 8 is a front elevation view of a reflective wall panel for the
oven device; and
FIG. 9 is a right side elevation view of a reflective wall panel
for the oven device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-5, an oven device 10 in accordance with one
embodiment of the invention includes an oven housing comprised of a
base 12, left and right side walls 14 and 16 attached to and
extending upward from the left and right edges of base 12, a rear
wall 18 attached to and extending upward from the rear edge of base
12 between side walls 14 and 16, and a top 20 attached to left and
right side walls 14 and 16 and rear wall 18 opposite base 12. Base
12, side walls 14 and 16, rear wall 18 and top 20 are formed of
food-grade stainless steel, each with an internal insulation layer
for containing heat generated by oven device 10.
Base 12, left and right side walls 14 and 16, rear wall 18 and top
20 together define a cavity 22 having a bottom portion 24, a lower
middle portion 26, an upper middle portion 28, and a top portion
30. Bottom portion 24 is disposed above and adjacent to base 12 and
is configured to support a lower heating unit 32. Lower middle
portion 26 forms a heating cavity 34 disposed above base heating
unit 32 and open to the front of oven device 10 for receiving one
or more food items 36. Although FIGS. 2 and 3 show food items 36 as
including food served in a casserole, food items 36 can include
many types of foods and complete meals which typically go through a
final finishing process in restaurants and cafeterias before being
served to customers. Such food items can be served on plates or
other support assemblies. For example, food items 36 can include
cheeseburgers served on plates, or Mexican dinners served on
platters. Food items 36 can also be served without any plates or
serving dishes. For example, food items 36 could be foil-wrapped
baked potatoes, with cheese or other toppings which can be melted
or browned by oven device 10.
Upper middle portion 28 of cavity 22 is disposed above heating
cavity 34 and is configured to support an upper heating unit 38.
Top portion 30 is disposed above and adjacent to upper heating unit
38 and is configured to support a control unit 40. Thus, cavity 22
of oven device 10 is configured to receive lower and upper heating
units 32 and 38 supported on bottom and top of heating cavity 34,
with lower and upper heating units 32 and 38 being configured to
provide heat from both the top and the bottom of any food items 36
placed within heating cavity 34. Control unit 40 is then used to
control the lower and upper heating units 32 and 38.
As described further below, control unit 40 has the capability of
independently controlling the heating cycles of heating units 32
and 38, preferably through the use of one or more
microprocessor-controlled heating sequences that are preprogrammed
or preset to meet the heating needs of particular types of food
items. In one embodiment, control unit 40 can be programmed to run
one of five different predetermined heating sequences via
activation of a corresponding one of five different push-button
switches by the food service operator, with each heating sequence
capable of independently varying the cycle times and power levels
of both heating units 32 and 38. The push-buttons can thus be used
to activate the proper heating sequence for each of five different
food items 36 with varying requirements.
Lower and upper heating units 32 and 38 each comprises a stainless
steel box or housing sized to fit within bottom and upper middle
portions 24 and 28 of cavity 22, respectively, so that heating
units 32 and 38 can be securely attached within oven device 10 by,
for example, welding or fasteners (e.g., screws, rivets). Referring
specifically to FIG. 3, the top surface of lower heating unit 32 is
formed of a lower glass panel 42, and the bottom surface of upper
heating unit 38 is formed of an upper glass panel 44. Glass panels
42 and 44 are attached to the edges of the respective housings of
heating units 32 and 38. One or more electrically-powered heating
elements 46 are mounted in lower heating unit 32, and one or more
such heating elements 48 are mounted in upper heating unit 38.
Heating elements 46 and 48 are adapted to focus radiant energy into
heating cavity 34 through respective glass panels 42 and 44. Each
heating element 46 and 48 receives a flow of electricity under the
control of a control board mounted within control unit 40.
When food items 36 are placed within heating cavity 34 between
lower and upper glass panels 42 and 44, heat generated by heating
elements 46 and 48 is directed or focused toward those food items
36 from both above and below the food items. The heat from lower
heating unit 32 performs the dual functions of heating the plate or
other support assembly and heating the food product itself, and the
heat from upper heating unit 38 browns or melts the top of the food
product.
Heating elements 46 and 48 are preferably resistive heating
elements which employ a thin, high-intensity resistive ribbon
element which heats up to an orange glow almost instantaneously
(e.g., in less than about 1.0 or 0.5 second). Oven device 10 is
thus able to reach its operating temperatures very quickly, which
provides an important advantage in the fast-food industry. Heating
elements 46 and 48 can be, for example, Halient elements available
from EGO North America. Alternatively, other types of heating
elements can be used, such as elements which use a resistive wire
coil. Preferably, the elements will be capable of being heated to
their operating temperatures quickly, with the maximum allowed
heating time depending on the application and the needs of the
particular restaurant or operator.
The size and number of heating elements 46 and 48 within heating
units 32 and 38 will depend on the particular food service
application, and to a large extent will depend on the sizes and the
shapes of the plates or other food support assemblies used. In one
embodiment of oven device 10 designed for a Mexican restaurant that
uses oversized oval platters for serving meals, heating elements 46
and 48 are selected as shown in FIGS. 3 and 5. In particular,
mounted in lower heating unit 32 is a single Halient heating
element having a nine (9) inch diameter and a power rating of 2500
W with a supply voltage of 240 V.sub.AC (EGO Part No.
10.53111.043), and mounted in upper heating unit 38 is an array of
four Halient heating elements, each having a six (6) inch diameter
and a power rating of 1250 W with a supply voltage of 240 V.sub.AC.
Heating elements having diameters of nine and six inches and power
ratings of 2400 W and 1200 W, respectively, with a 208 V.sub.AC
supply are also available. Note the geometrical arrangement of the
upper heating elements 48 (as best shown in FIG. 5) provides good
heat coverage even for the oversized oval platters which are used
by the above-referenced Mexican restaurant.
In an alternate embodiment of oven device 10 designed for use with
regular circular serving plates (not shown), a single Halient
heating element with a diameter of nine (9) inches is mounted in
each of lower and upper heating units 32 and 38, with the two
heating elements mounted opposite each other. Where the serving
plates have a diameter larger than that of the heating elements,
the rims of the plates placed between these two heating elements
will not receive direct radiant energy from the heating elements.
In this case, the rims of the plates will tend to remain relatively
cool during the short time required to perform the final finishing
process (i.e., melting or browning the food items), thus allowing
the food service workers to handle the plates by their rims without
the need for insulated gloves or other methods (e.g., using tongs
to handle the heated plates). For example, if an 11 inch diameter
plate is placed between lower and upper nine inch diameter heating
elements for the short time needed to melt cheese placed on top of
a pre-cooked hamburger patty, the rim of the plate will tend to
remain cool enough to allow handling by a food service worker
without the need for any special equipment.
Other types, sizes, numbers and geometrical arrangements of heating
elements 46 and 48 are possible depending upon the particular oven
application, and on the size and shape of the serving plates
regularly used in that application. Such alternative oven
configurations will be readily apparent to those of skill in the
art.
Lower and upper glass panels 42 and 44 are clear glass panels which
pass most of the radiant energy generated by heating elements 46
and 48 to heating cavity 34 to heat any food items 36 placed
therein by the food service operator. In one embodiment, glass
panels 42 and 44 are tempax barosilicate glass panels made by
Schott America of New York, sold under the SCHOTT glass tradename.
These panels are formed of a clear, quartz glass that transmit or
pass about 99% of the radiant energy. Other types of glass could
also be used, including Ceran glass, although Ceran glass may not
transmit radiation as efficiently as the Schott glass.
As discussed above, the application of electrical power to heating
elements 46 and 48 in heating units 32 and 38 is controlled by
control unit 40. Unit 40 comprises a stainless steel housing sized
to fit within top portion 30 of cavity 22, such that unit 40 can be
securely attached within oven device 10 using, for example, welding
or fasteners (e.g., screws, rivets). Control unit 40 has a front
surface 50 that provides an operator interface having a number of
input devices (e.g., switches) for allowing the operator to control
the operations of oven device 10, and a number of output devices
(e.g., displays) for displaying status information to the
operator.
Control unit 40 includes an electronic controller/output circuit
board (not shown) mounted within its housing and an operator
interface board 52 mounted to front surface 50. Operator interface
board 52 is mounted such that the input devices (e.g., switches) on
board 52 are accessible to the operator (e.g., through apertures in
front surface 50), and such that the output devices (e.g.,
displays) on board 50 are visible to the operator (e.g., also via
apertures in front surface 50). Of course, the input and output
devices could also be mounted directly onto front surface 50.
Control unit 40 provides programmable control of upper and lower
heating units 32 and 38, using timer circuits or a
microprocessor-based controller. In one embodiment, control unit 40
provides the operator or food service worker with a plurality
(e.g., five) of programmable sequences for independently operating
lower and upper heating elements 46 and 48, with a corresponding
plurality (e.g., five) of push-buttons provided to allow for
one-touch control for each sequence.
Each sequence can be programmed for a different type of food item,
thereby allowing the food service operator to select one of the
plurality (e.g., five) of predetermined sequences simply by pushing
a push-button. For example, oven device 10 could be configured or
programmed such that one push-button triggers a first preset
sequence for operating lower and upper heating elements 46 and 48
in a first manner suitable for final finishing of fajitas, a second
push-button triggers a second present sequence for operating
elements 46 and 48 in a second manner suitable for final finishing
of enchiladas, etc. In this way, oven device 10 can be programmed
to provide a simple operator interface allowing even operators with
little experience and training to accurately control the heating of
many food items.
As best shown in FIG. 6, operator interface board 52 supports an
alphanumeric display 54, two amber LEDs 56a and 56b, eight
push-button (i.e., momentary) input switches 58a-58h, and five
green LEDs 60a-60e. Display 54 includes a number (e.g., four) of
seven-segment LEDs. Lower amber LED 56a indicates status of lower
heating element(s) 46 and upper amber LED 56b indicates status of
upper heating element(s) 48. The push-button input switches
comprise five program switches 58a-58e, an up-arrow switch 58f, a
down-arrow switch 58g, and an enter switch 58h. The five green LEDs
60a-60eindicate the status of each of the five programs selectable
by the operator using program switches 58a-58e.
The electronic controller/output circuit board mounted within
control unit 40 includes four line voltage output circuits, a timer
circuit and an annunciator (e.g., a buzzer circuit). Each line
voltage output circuit includes a load-carrying triac. Triacs are
solid-state switches capable of reliably handing a large number
(e.g., hundreds of thousands) of power cycles without failure. For
oven device 10, the controller/output circuit board receives four
voltage inputs including a 12-24 V input voltage, a first 208-240
V.sub.AC line voltage input (L1), a second 208-240 V.sub.AC line
voltage input (L2), and a third 208-240 V.sub.AC line voltage input
(L3), and then generates four voltage outputs including a first
line voltage output for two upper heating elements 48 (circuit A),
a second line voltage output for two upper heating elements 48
(circuit B), a third line voltage output for lower element 46
(circuit C) and a fourth line voltage output for lower element 46
(circuit D). Each of the triacs has the capability to handle a 12 A
resistive load.
The timer circuit on the controller/output circuit board operates
the triacs semi-independently to control the supply of line
voltages applied to heating elements 46 and 48. In one embodiment,
the timer circuit is a programmable timer configured to run from 0
to 300 seconds in single second increments. Preferably, the timer
circuit includes a microprocessor circuit configured (i.e.,
programmed) to perform the various functions described below. As
noted, the timer circuit provides a plurality (i.e., five) of
programmable sequences for operating the upper and lower heating
elements, with each "run-time" sequence being triggered by the edge
signal from one of the five program switches 58a-58e. In the
microprocessor embodiment of the timer circuit, the microprocessor
stores five different programs, each used for a different type of
food item 36. Each program allows the restaurant owner to select
the on-time, off-time and amount of power to be applied to food
items 36 by each of heating elements 46 and 48. By carefully
managing the heating elements, food items 36 can be heated quickly
without being burned. Along with the five programmable sequences
for both sets of elements (i.e., lower and upper), control unit 40
also provides a programmable stand-by sequence, an auto-off mode,
and a curing mode sequence. Each of these sequences is further
described as follows:
Run-Time Sequence: Lower and upper heating elements 46 and 48 both
have 5 separately programmable timing sequences and 10 selectable
power levels. The particular values for the timing sequences and
selectable power levels used for the final finishing (e.g.,
browning, melting) of a particular food item 36 are determined via
empirical testing.
Timing Sequences: The time values for lower and upper heating
elements 46 and 48 represent their "on" times and the time value
for both heating elements 46 and 48 is any value between 0 and 300
seconds. When a sequence is triggered, the lower and upper heating
elements are both de-energized at the same time. For example, if
the "on" time for the upper element is 45 seconds, and the "on"
time for the lower element is 65 seconds, the lower element is
energized 20 seconds before the upper element so both elements are
de-energized at the same time.
Selectable Power Levels: The power levels of heating elements 46
and 48 are selected by varying the duty cycle of the on time and
may be set in 5% or 10% power level increments. For example, a 10%
power level is achieved by cycling on for 4 seconds and off for 36
seconds, 20% power level is achieved using 4 seconds on and 16
seconds off, 30% power level is achieved using 4 seconds on and 9
seconds off, 40% power level is achieved using 4 seconds on and 6
seconds off, 50% power level is achieved using 4 seconds on and 4
seconds off, 60% power level is achieved using 6 seconds on and 4
seconds off, 70% power level is achieved using 9 seconds on and 4
seconds off, 80% power level is achieved using 10 seconds on and
2.5 seconds off, 90% power level is achieved using 18 seconds on
and 2 seconds off, and 100% power level is achieved by remaining
the heating elements 46 and 48 continuously on.
Stand-By Mode: When a run-time sequence is not being performed,
oven device 10 remains in a stand-by mode. During the stand-by
mode, the upper elements cycle at a selectable power level, and the
display indicates that the oven is in stand-by mode by displaying
"rEdY". The power levels which can be selected during the stand-by
mode include the 10%, 20%, 30%, 40%, 50%, 60% and 70% on time power
levels. The purpose of stand-by mode is to maintain the internal
temperature of oven device 10 at an elevated temperature (e.g.,
300-400.degree. F.) in order to further reduce the cooking time of
the food items. This elevated temperature depends on the
above-described cycle time. In an alternative embodiment, the
heating elements are not powered in the standby mode, further
conserving energy used by oven device 10.
Auto-Off Mode: When oven device 10 is not used for a specified
period of time, the stand-by mode is discontinued and the auto-off
mode begins. In the auto-off mode, the display indicates "OFF" and
the heating elements are not energized. Actuation of any of
push-buttons 58a-58e will reactivate the stand-by mode by beginning
the curing mode sequence. The specified time is factory set to a
value between 0 and 60 minutes. Of course, the specified
time-period could also be user modifiable.
Curing Mode Sequence: The controller automatically executes a
curing mode when oven device 10 is turned on (using, for example, a
rocker switch 62 mounted to front surface 50 of control unit 40,
shown in FIG. 62), or when exiting the auto-off sequence. During
curing mode sequence, the heating elements are turned on at full
power for 60 seconds, then full off for 10 seconds. and the display
reads "StbY" to indicate the standby status of oven device 10.
During the curing mode, oven device 10 cannot be put into its
normal run sequence. When the curing sequence has been completed,
the controller automatically goes into the stand-by mode.
The setup (i.e., programming) procedure for the run-time sequence
is as follows: First, the appropriate program switch 58a-58e and
enter switch 58h are pushed simultaneously. For example, if program
no. 1 is to be adjusted, program switch 58a and enter switch 58h
are pushed at the same time for 3 seconds; if program no. 2 is to
be adjusted, program switch 58b and enter switch 58h are pushed at
the same time for 3 seconds, etc. Second, after the appropriate
program has been selected, the green LED 60a-60e over the selected
program switch 58a-58e is illuminated, upper amber LED 56b is lit
and alphanumeric display 54 indicates the power level value which
is currently programmed ("P.sub.13 40" for the 40% power level)
scrolls to the next programmable sequence. Each sequence includes
four values: (1) the upper power level value (upper amber LED 56b
is lit; display 54 shows, e.g., "P.sub.13 40"); (2) the upper time
value (upper amber LED 56b is lit; display 54 shows, e.g.,
"T.sub.13 65"); (3) the lower power level value (lower amber LED
56a is lit; display 54 shows, e.g., "P.sub.13 40"); and (4) the
lower time value (lower amber LED 56a is lit; display 54 shows,
e.g., "T.sub.13 65"). Fourth, at each step, up and down arrow
buttons 58f and 58g can be used to increase or decrease the values.
Fifth, when all of the values have been properly adjusted,
activation of the respective program button 58a-58b causes the
controller to accept the changes. After 15 seconds of no activity,
however, the controller is programmed to exit the programming mode
without accepting the changes. Sixth, activation of any of the
other, non-selected program buttons 58a-58e during the programming
process will cause the adjustments to be manually cancelled. After
being programmed, the user actuates each program button 58a-58e to
activate the desired heating sequence.
The setup procedure for the standby mode is as follows. First,
enter button 58h and up arrow button 58f are pushed simultaneously
for 3 seconds. Second, display 54 indicates the power level value
currently programmed (e.g., "P.sub.13 40") for use during the
standby mode. The power level can then be adjusted by pushing up
and down arrow buttons 58f and 58g. Third, enter button 58h is
activated to accept the new value. Fourth, if no adjustments are
made after 15 seconds, the controller exits the standby programming
mode without accepting the changes. Fifth, activation of any
program switch 58a-58e during the standby programming will cause
the controller to exit standby setup mode without accepting any of
the changes that were made.
The operation of the displays and lamps is as follows. First, if a
program has not been selected, oven device 10 is in standby mode
and LED display 54 will show "rEdY". Second, on release of any of
the five "start buttons" (i.e., program buttons 58a-58e), LED
display 54 will show the time (e.g., "T.sub.-- 83"), and the
display will begin to count down in one second increments. Third,
when the time has elapsed, display 54 will flash or blink the
message "dOnE" for 6 seconds, all of the green LEDs 60a-60e will
flash for 6 seconds and the annunciator will beep for 6 seconds.
Pressing any of buttons 58a-58h during this 6 second period will
cancel the annunciator but will not start the program sequence.
Fourth, after the 6 seconds have elapsed, display 54 will indicate
"rEdY". Then, whenever the upper element(s) 48 are energized, upper
amber LED 56b will be energized and whenever the lower element(s)
46 are energized, the lower amber LED 56a will be energized.
The operation of the annunciator is as follows. First, the
annunciator will beep in response to every push of one of buttons
58a-58h to verify the entry. Second, when a normal timing sequence
has been completed, the annunciator will energize as described
above. Third, preferably, the annunciator circuit includes a DIP
switch or other device to allow the user to remove the annunciator
function.
During a normal run time sequence, pushing any of buttons 58a-58h
prior to the completion of the timing cycle will cancel that run
time sequence, and will cause the controller to enter the standby
mode. At that point, the operator can press another of the program
buttons 58a-58e to start another heating sequence.
A number of components are mounted external to oven device 10. The
external components include a plurality (i.e., four) of rubber or
plastic supports 64 attached to the four corners of base 12 to
provide support for oven device 10 on a support surface (not
shown), such as a restaurant kitchen countertop. A pair of axial
fans or blowers 66 are mounted to the back of rear wall 18 so that
axial fans 66 can blow ambient air through heating cavity 34. The
airflow provided by axial fans 66 evenly distributes the heat
within heating cavity 34, thereby preventing the back of the
serving plates placed within heating cavity 34 from getting too hot
while preventing the front of the serving plates from getting too
cool (which otherwise may occur since heating cavity 34 is open in
the front and closed in the rear). The air flow cools the glass
panel 44 for upper heating element 48, and prevents the heat from
being applied unevenly to food products 36 being heated.
Alternatively, in a pass-through oven wherein both the front and
back of the heating cavity are open (to allow food products to be
inserted at one end and taken out from the other end), its likely
that no axial fan will be needed since the heat will be more evenly
distributed.
An electrical power cord 68 passes through a grommet 70 into the
interior of control unit 40 to provide the electrical energy needed
to run oven device 10. To provide a cooling air flow to the
interior components of control unit 40, the rear surface of control
unit 40 can be provided with louvers 72, and a cooling fan 74 can
also be mounted on that rear surface to blow cooling air into
control unit 40.
As shown in FIGS. 1-5, a wire rack 76 is provided to support food
items 36 above lower glass panel 42. Wire rack 76 preferably slides
into heating cavity 34 using rails or other mounting guides along
the cavity's inside surfaces. Alternatively, the food items can be
supported directly on lower glass panel 42.
Thus, the on and off operation of heating elements 46 and 48 can be
independently controlled by a timing circuit which provides
predetermined timing and power level sequences appropriate for the
heating application. The timing can be started manually by the
operator using a switch 58a-1458e mounted to the housing of the
oven. Alternatively oven device 10 can be started automatically by
a switch coupled to wire rack 76 which is actuated when the food
carrying device is placed into the oven onto rack 76. The latter
switch can be activated, initiating the heating cycle, by the
weight of the food carrying device on rack 76. Further, the latter
switch could be a micro-switch activated by a paddle or other
device as the paddle is struck by the food carrying device when
that device is inserted into the oven.
In one embodiment, heating elements 46 and 48 are individually
controlled by a series of timers operable to delay the start and
independently cycle the heating elements to give the precise amount
of heat required to be applied to the upper and lower surfaces of
the food product without burning or scorching the food product. In
one embodiment, the oven device could be configured to
automatically eject the food products from the appliance at the end
of the heating process.
Referring to FIGS. 7-9, a reflective wall panel 80 for the oven
device is shown according to a further embodiment of the invention
for improving the balance and distribution of browning and cooking
of food items 36 placed within heating cavity 34 by dispersing and
dissipating the radiant heat energy emitted from heating units 32
and 38. Reflective wall panel 80 may be integrated into oven device
10 in particular to replace the need for blowers 66. Accordingly,
wall panel 80 is used to disperse heating properties such that fans
66 are not needed to provide even heating of items placed into
heating cavity 34. In an exemplary embodiment, wall panel 80 may
replace rear wall 18 of FIG. 1. A vertically-oriented frame member
82 is formed having a generally rectangular profile with an upper
mounting surface 84, a lower mounting surface 86, a first side
mounting surface 88 and a second side mounting surface 90. The
frame member 82 includes a generally planer border portion 92
surrounding a generally rectangular opening 94 that may have
rounded corners.
A reflective panel insert 96 is formed having a corrugated surface
98 shown schematically in FIG. 7, and defined by a series of
alternating peaks 100 and valleys 102 for providing a radiant heat
reflective surface for more uniformly dispersing and dissipating
radiant heat energy emitted by heating units 32 and 38 for
improving the balance and distribution of browning and cooking of
the food items 36 placed within heating cavity 34. Peaks 100 and
valleys 102 are shown preferably having a linear and horizontal
orientation, but may also be configured having a linear and
vertical orientation (not shown). In alternative embodiments, the
reflective pattern of peaks 100 and valleys 102 may be circular or
any other suitable pattern for enhancing the radiant heat energy
dispersal and dissipation necessary to meet the heating needs of
particular food items according to the particular geometrical
proportions of cavity 22 and the configuration of heating elements
46 and 48.
Reflective panel insert 96 may be removably attached to an inner
side of frame portion 92 by, for example, welding or fasteners
(e.g., screws, rivets, etc.). The separability of frame portion 92
from reflective panel insert 96 facilitates the interchange of
panel inserts having varying reflective patterns within a single
frame member for customizing the radiant heat dissipation and
dispersion properties of the ovens to suit the variety of
applications necessary for the food service industry.
Alternatively, panel insert 96 and frame portion 92 may be made
from an integrally formed member.
A bracket member 104 is securely attached horizontally along a
lower portion of frame member 82 and reflective panel insert 96 to
complete the reflective wall panel 80. The elevation of bracket
member 104 is located to interface with, and support, lower glass
panel 42. Bracket member 104 may be provided with apertures 108
aligned with apertures 110 on frame member 82 for securing bracket
member 104 to frame member 82 with fasteners. Alternatively,
bracket member 104 may be secured to frame member 82 in any other
suitable manner such as welding or riveting. Bracket member 104 may
also be attached horizontally to an upper portion of frame member
82 to support upper glass panel 44. For embodiments of oven device
10 having vertically planer heating units (not shown), bracket
member 104 may be oriented vertically on frame member 82 to support
corresponding vertically planar glass panels (not shown).
Frame member 82, reflective panel 96 and bracket member 104 are
preferably manufactured from food grade stainless steel sheet stock
(e.g., type 304) having a thickness of approximately 0.036 inches
and a 2B surface finish according to any well known stamping and
bending process. However, frame member 82, reflective panel 96 and
bracket member 104 may be formed of other suitable materials (e.g.,
aluminum, aluminized steel, chrome-plated carbon steel, etc.) and
having any suitable thickness and surface finish for providing
suitable radiant heat reflecting properties and for interfacing
with adjacent components of oven device 10.
Reflective wall panel 80 may be adapted to fit along the interior
of oven device 10 in a generally parallel orientation to one or
more of the base 12, the left side wall 14, the right side wall 16,
the rear wall 18 and the top 20, whereby the face of reflective
panel insert 96 is exposed through opening 94 toward cavity 22 of
oven device 10 for obtaining the desired radiant heat energy
distribution performance. A plurality of fastener apertures 106 may
be provided along upper mounting surface 84, lower mounting surface
86, first side mounting surface 88 and second side mounting surface
90 for attaching wall panel bracket 82 to the base 12, the left and
right side walls 14 and 16, rear wall 18 and top 20.
In alternative embodiments, a reflective panel member may be
unitarily or integrally formed with a frame member for mounting
within the desired locations of the oven and the relative angle and
spacing of the corrugation peaks and valleys on the reflective
panels may be adjusted or modified to any appropriate pattern for
obtaining the desired radiant heat distribution performance for
uniformly cooking, heating or browning a variety of food items.
Thus, oven device 10 is capable of rapidly melting or browning the
top surface of food items or complete meals, while also heating the
serving plates or other food support assembly in addition to
heating the food product itself. Testing of a prototype showed that
oven device 10 reduced the heating time for melting or browning by
a factor of three compared to the time needed by a conveyor oven.
The reduced heating time is due to the rapid heating of heating
elements 46 and 48, combined with the microprocessor-based control
sequences which allow both the heating times and power levels to be
programmed for different types of food items. The high level of
control allows the rapid-heating and high power-output heating
elements to rapidly heat the food items without scorching or
burning the food items. The Halient heating elements used by oven
device 10 reach operating temperatures within a few seconds (e.g.,
about 1-3 seconds from room temperature), and testing of a
prototype showed that the air within the heating cavity reached a
temperature of about 450.degree. F. at a 25% power level within 1-2
seconds of the power being applied.
Oven device 10 also provides significant advantages with respect to
the Salamander broiler. For example, while the Salamander broiler
must be left on continually, oven device 10 can be turned on and
off as needed, thereby decreasing both energy usage and the amount
of heat vented into the kitchen. The decreased heat vented into the
kitchen allows the exhaust hood or other ventilation method needed
for the Salamander broiler to be dispensed with, and results in
savings in air conditioning and ventilation costs. Another
advantage of oven device 10 is that the edge of the serving plate
or other food support assembly (i.e., the rim) need not be directly
exposed to the radiant energy generated by the heating elements.
This allows the operator to pick up the plate or dish by its rim
without the need for insulated gloves or other means, which would
not be possible with a conveyor oven.
While the embodiments shown in the FIGs. and described above are
presently preferred, it should be understood that these embodiments
are offered by way of example only. The invention is not intended
to be limited to any particular embodiment, but is intended to
extend to various modifications that nevertheless fall within the
scope of the appended claims. For example, different configurations
of the oven can be used, such as closed-end or pass-through ovens.
The types, sizes, numbers and geometrical arrangements of the
heating elements can be modified depending on the application of
the oven device. The type of control unit can be changed, and
different types and numbers of programmable or non-programmable
timers can be used. Other modifications will be evident to those of
skill in the art.
* * * * *